The National Institute of Standards and Technology coordinates the Micronutrients Measurement Quality Assurance Program (MMQAP) for laboratories that measure fat- and water-soluble vitamins and carotenoids in human serum and plasma. This report describes the design of and results for the Winter 2012 MMQAP measurement comparability improvement studies: 1) Round Robin LXXII Fat-Soluble Vitamins and Carotenoids in Human Serum and 2) Round Robin 37 Total Ascorbic Acid in Human Serum. The materials for both studies were shipped to participants in June 2012; participants were requested to provide their measurement results by September 28, 2012.